1. Field of the Invention
The present invention relates to pliers for gripping and holding articles and more particularly to pliers for extracting antenna elements from an antenna panel.
2. Description of the Prior Art
The antenna to the PATRIOT missile system includes a panel having a matrix array of deep, generally cylindrical-shaped, receptacles therein. The receptacles retain plug-in electronic components known as antenna elements or radar elements. Each antenna element has a cylindrical head having a pair of spaced apart circumferential channels therein, which accomodate a retaining ring to insure a snug, stable fit and a sealing ring for weatherproofing purposes. The portion of the head which extends out from the receptacle includes another circumferential channel therein which serves as a gripping channel to facilitate removal of the antenna element.
The overhaul of the antenna to the PATRIOT missile system requires the removal of all of the antenna elements from the antenna panel. Since each panel contains a total of 5,463 receptacles and associated antenna elements, removal of the antenna elements was a tedious, time consuming process which was undertaken one by one with a costly, specially designed puller assembly. Approximately four worker days were consumed to complete the removal of all antenna elements from an antenna panel using the puller assembly.
The puller assembly was a somewhat complex and costly mechanism which included a base adapted to abut the panel in a predetermined orientation and encompass the head of the antenna element, three spring tensioned fingers extendable into firm engagement with the gripping channel at three predetermined points 120 degrees apart, and a worm gear mechanism to slowly withdraw the antenna element from the receptacle. The puller assembly worked reasonably well under favorable conditions, but less so under the conditions generally encountered during an overhaul.
Since the antenna to be overhauled was used in all-weather environments it was subjected to the harmful effects of wind, rain, dust, and dirt over extended periods of time such that during the overhaul, many of the antenna elements were frozen in place and difficult to remove, primarily because of the grit and grime that had become embedded proximate the sealing ring. Under such circumstances, use of the puller assembly was likely to result in damage to the head of the antenna element during removal such that it was no longer usable. In numerous instances the puller assembly would fail to extract the damaged antenna element since the spring tensioned fingers would only engage the gripping channel at the three predetermined points which, after being stripped by a failed extraction effort, no longer provided a lifting surface for the fingers to adequately engage. On average, use of the puller assembly resulted in approximately 400 antenna elements being damaged for each panel being overhauled, which was unacceptably high, especially in view of the high replacement cost for damaged antenna elements.